How to use the petab.Problem.from_folder function in petab

def test_0_import(self):
        for model_name in ["Zheng_PNAS2012", "Boehm_JProteomeRes2014"]:
            petab_problem = petab.Problem.from_folder(
                folder_base + model_name)
            self.petab_problems.append(petab_problem)

output_folder: str = None,
                    model_name: str = None):
        """
        Simplified constructor exploiting the standardized petab folder
        structure.

        Parameters
        ----------

        folder: str
            Path to the base folder of the model, as in
            petab.Problem.from_folder.
        output_folder: See __init__.
        model_name: See __init__.
        """
        petab_problem = petab.Problem.from_folder(folder)

        return PetabImporter(
            petab_problem=petab_problem,
            output_folder=output_folder,
            model_name=model_name)

def from_folder(folder, output_folder=None):
        """
        Simplified constructor exploiting the standardized petab folder
        structure.

        Parameters
        ----------

        folder: str
            Path to the base folder of the model, as in
            petab.Problem.from_folder.

        output_folder: see __init__.
        """
        petab_problem = petab.Problem.from_folder(folder)

        return PetabImporter(
            petab_problem=petab_problem,
            output_folder=output_folder)